#include <stdio.h>
#include <math.h>
int main()
{
    int i,count ;
    printf(" there are invertable primes with 4 digits: \n");
    for(count=0,i=1001;i<9999;i+=2)
    if(num(i))
    printf(count%9?"%3d:%d":"%3d:%d\n",++count,i);
}

num(int number)
{
    int j,i;
    if(! ok(number))
    return (0);
    for(i=number,j=0;i>0;i/=10)
        j=j*10+i%10;
        if(number<j)
        if(!ok(j))
        return 0;
        else 
        return 1;
        else
        return 0;

}
ok(int number)
{
    int i,j;
    if(number%2==0)
    return 0;
    j=sqrt((double)number)+1;
    for(i=3;i<=j;i+=2)
        if(number%i==0)
        return 0;
        return 1;
}